An Efficient Microwave Synthesis of 3-Acyl-5-bromoindole Derivatives for Controlling Monilinia fructicola and Botrytis cinerea

Molecules containing indole cores are of interest due to their multiple biological applications and seem to be an alternative to face contemporary challenges in agriculture, especially the control of phytopathogens that affect fruit quality. In this research, starting from 5-bromoindole (<b>A</b>), eleven 3-acyl-5-bromoindole derivatives with linear (<b>B</b>-<b>G</b>) and aromatic (<b>H</b>-<b>L</b>) substitutions were obtained through microwave-assisted synthesis. The antifungal capacity of indole, 5-bromoindole (<b>A</b>) and their derivatives (<b>B</b>-<b>L</b>) were determined by in vitro assays on <i>Monilinia fructicola</i> and <i>Botrytis cinerea</i>, and a molecular docking was performed on mitochondrial complex II, succinate dehydrogenase (SDH). The results indicate that compounds <b>A</b>, <b>B</b>, <b>G</b>, and <b>L</b> were able to inhibit the growth of <i>M. fructicola</i>, while only <b>A</b> and <b>J</b> showed activity against <i>B. cinerea</i>. The acylation of <b>A</b> improved their ability to inhibit the germination of conidia on both pathogens. Compounds <b>A</b>, <b>B</b> and <b>G</b> are the most promising candidates for future research due to their inhibition on <i>M. fructicola</i> and/or <i>B. cinerea</i> and demonstrate favorable binding energies with SDH.